Aero wheels have become the norm; every pro order and many amateurs ride them everyday. for weight and aero. But riders always worry about being “blown around”, and the real aero benefits never seem as big as the theory.
At Sōr, we see that reality and we’ve designed wheels that anyone can ride in any conditions. Wheels that are really fast- way faster than you’ve ever seen before.
How is that possible?
Since the mid 1980’s the bike industry has been working to rethink wheels to reduce the drag, but most of the work was concentrated at relatively low yaw angles (ie, not much sidewind). But we felt that the real-world side winds were higher than the theoretical models and that typical rider speeds were lower than the speeds used in testing. When you accept that the real-world sidewinds are higher than everyone assumes, you understand why riders constantly complain about the sidewind buffeting and loss of stability.
We’ve measured those real world conditions:
As you can see, the yaw angle is a lot higher than in theory. We design a wheel to work at the yaw angle that you are actually feeling. The Sōr wheel design immediately adapts to the conditions you are feeling at that second. If the conditions change a second later, the wheel shape changes to a new optimal shape. The net result is you don't get the instability and buffeting that everyone talks about with aero wheels because the wheel is constantly adapting to the immediate conditions.
Technically, that buffeting is caused by the air separating from the wheel - the same thing that happens when a plane wing stalls. The result is instability, turbulence, and drag.
How does the wheel work?
For many years aircraft have been modifying the shape of wings to optimize the performance for takeoff, cruise, and landing. Typically that has been done with mechanical mechanisms and control systems.
But no-one has been able to mimic the way the wing of a bird or bat can instantaneously and passively optimize itself to the wind conditions.
We’ve designed a wheel to mimic the bat wing and passively react to the conditions.
The wheel’s morphing sidewall automatically and passively adapts to the conditions.
You can see the difference in the shape on both sides of the wheel here.
Here is a clip of the sidewalls reacting immediately to airflow changes:
That means that the surfaces are always the optimal shape. Most of the wheel’s load is carried by a central hidden structure that does not have to worry about being aerodynamic. The separation on the duties means that each is optimized for its role and the overall wheel weight can be much lower while also being more aerodynamic.
How much more aerodynamic is it? How much more stable is it?
A wheel with great aerodynamics is not good to the rider if they feel unstable and they are battling to stay on the bike rather than battling the competition. The rider has to have the confidence to remain in the aero position and focus on the job at hand and not worry about their equipment. If you are tensing and fighting the bike that wasted effort and lack of focus is slowing you down. The Sōr wheel stops the buffeting and instability by keeping the air attached, just like a plane's wing changes shape during take off & landing or a bat wing does continually.
A Sōr disc keeps the air attached up to about 28 degrees of apparent wind compared to about 15 degrees for the best shaped rigid disk, and a lot less for most. That means you don't get the buffeting that you get from a traditional disk wheel. Even after Sōr wheels have stalled you can visibly see the massive reduction in buffeting compared to rigid wheels. We are working with a university lab that specializes in unsteady aerodynamics on quantifying the improvement in stability. You get the same reduction in buffeting on a deep dish wheel as well.
How much faster will it make me?
Once you know that you can stay in your aero position and focus you will have the confidence to go faster. And your Sōr wheel will provide a forward thrust that shocks riders the first time they ride one. Like any wheel, the gains depend on your speed, the course, and the conditions. If you want to translate those numbers to your speed and conditions, here is a good simple calculator to help you.
We did most of our recent testing at the San Diego Low Speed Wind Tunnel (including some mishaps)
and the Sōr road disk keeps the wind attached up to 28 degrees and delivers almost 90 Watts (!) of thrust at that point.
You can see those results here:
In the end, a Sōr disc delivers you a revolution in aerodynamics - lightweight stable speed.